This invention relates to an emergency descent device, particularly to one having a fluid rotation-retarding device for controlling the rate of descent.
Emergency descent devices having a rotating spool with a cable wound thereon and a fluid rotation-retarding means are known in the prior art. U.S. Pat. Nos. 4,018,423, 3,847,377 and 3,946,989 disclose descent devices having fluid rotation-retarding units which include one or more vane members dividing a fluid-filled, sealed housing into two or more variable volume chambers which are then communicated by providing one or more passages. These passages are adjustable to control the rotation rate of the vane. However, the adjustment of the passage is usually done manually. In the parent application of the present application, a self-adjusting fluid rotation-retarding unit is suggested, having telescopic vane members extensible by the centrifugal force induced by the descending of the load. The telescopic vane members when extended provide an increased surface area to interact with the fluid, thereby increasing the retarding effect of the retarding unit. The retarding capacity of the retarding unit is self-adjusted by means of the centrifugal force.